SMD code BFs
Marking codes are not standardised, and the same code is reused by unrelated makers for unrelated parts. Below is every part in our tables printed with it, and any printed with a code that is easy to misread as it, from the manufacturers' own marking tables and published code lists.
The last letter, s, is lower case, which on NXP and Philips parts is a date or factory code, so it was set aside and BF was searched.
122 parts are printed BFs
Not sure which one you have?
Answer up to 4 quick questions and these 50 parts are ranked, with a meter test that settles it. It works on a dead part too.
MMBZ5246BSOT-23Zener diode, 3 pins, Formosa MicrosemiZener diodeSOT-233 pinsFormosa Microsemi
- What it is
- Zener diode
- Maker
- Formosa Microsemi
- Package
- SOT-23
- Pins
- 3
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
PMEG4030ERSOD-123WSchottky diode, 2 pins, NexperiaSchottky diodeSOD-123W2 pinsNexperia
- What it is
- Schottky diode
- Maker
- Nexperia
- Package
- SOD-123W
- Pins
- 2
- Details
- 40 V, 3 A low VF Schottky barrier rectifier
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Schottky diode.
S-LBC847BPDW1T1GSOT-363Transistor, 6 pins, LRCTransistorSOT-3636 pinsLRC
- What it is
- Transistor
- Maker
- LRC
- Package
- SOT-363
- Pins
- 6
- Details
- Bipolar transistor, P+N, IC 100 mA, VCEO 45 V
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
S-LBZT52MB6V8T1GSOD-123Zener diode, 2 pins, LRCZener diodeSOD-1232 pinsLRC
- What it is
- Zener diode
- Maker
- LRC
- Package
- SOD-123
- Pins
- 2
- Details
- Zener diode, VZ Min 6.66 V, VZ Max 6.94 V, Vz@IZT mA 5
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
S-LUDZS6.8MBT1GSOD-323Zener diode, 2 pins, LRCZener diodeSOD-3232 pinsLRC
- What it is
- Zener diode
- Maker
- LRC
- Package
- SOD-323
- Pins
- 2
- Details
- Zener diode, VZ Min 6.66 V, VZ Max 6.94 V, Vz@IZT mA 5
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
SMAJ13SMATVS diode, 2 pins, DOWOTVS diodeSMA2 pinsDOWO
- What it is
- TVS diode
- Maker
- DOWO
- Package
- SMA
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SMBJ13CSMBTVS diode, 2 pins, DOWOTVS diodeSMB2 pinsDOWO
- What it is
- TVS diode
- Maker
- DOWO
- Package
- SMB
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SMCJ43CSMCTVS diode, 2 pins, DOWOTVS diodeSMC2 pinsDOWO
- What it is
- TVS diode
- Maker
- DOWO
- Package
- SMC
- Pins
- 2
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: TVS or ESD protection diode.
SN74AHCT1G14DCKSOT-353Logic gate, 5 pins, Texas InstrumentsLogic gateSOT-3535 pinsTexas Instruments
- What it is
- Logic gate
- Maker
- Texas Instruments
- Package
- SOT-353
- Pins
- 5
- Details
- Single Schmitt-Trigger Inverter Gate
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Integrated circuit.
TLV70729DQNX2SONLDO regulator, 4 pins, Texas InstrumentsLDO regulatorX2SON4 pinsTexas Instruments
- What it is
- LDO regulator
- Maker
- Texas Instruments
- Package
- X2SON
- Pins
- 4
- Details
- 200-mA, Low-IQ, Low-Noise, Low-Dropout Regulator for Portable Devices
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Voltage regulator.
UDZ7V5BSOD-323Zener diode, 2 pins, Galaxy MicroelectronicsZener diodeSOD-3232 pinsGalaxy Microelectronics
- What it is
- Zener diode
- Maker
- Galaxy Microelectronics
- Package
- SOD-323
- Pins
- 2
- Details
- 7.5V, 200mW, Surface Mount Zener Diodes
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Zener diode.
2SB1123-SSOT-89Transistor, 3 pins, YFWTransistorSOT-893 pinsYFW
- What it is
- Transistor
- Maker
- YFW
- Package
- SOT-89
- Pins
- 3
- Details
- Bipolar transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: Bipolar transistor.
BTB5839M3SOT-89PNP transistor, 3 pins, CYStekPNP transistorSOT-893 pinsCYStek
- What it is
- PNP transistor
- Maker
- CYStek
- Package
- SOT-89
- Pins
- 3
- Details
- -30 V, -3 A PNP transistor
- Source
- Manufacturer datasheet
Is it dead? The meter test is below: PNP transistor.
1.5SMCJ43CSMCTVS diode, 2 pins, PanjitTVS diodeSMC2 pinsPanjit
- What it is
- TVS diode
- Maker
- Panjit
- Package
- SMC
- Pins
- 2
- Details
- TVS: 43V, 19.6A, 1500W (1ms), Bidirectional
- Source
- Published code list
Is it dead? The meter test is below: TVS or ESD protection diode.
1SS268SOT-233 pins, ToshibaNot recordedSOT-233 pinsToshiba
- What it is
- Not recorded
- Maker
- Toshiba
- Package
- SOT-23
- Pins
- 3
- Details
- dual cc pin sw
- Source
- Published code list
Is it dead? The meter test is below: This part.
Is it dead? One meter test per kind
Parts of the same kind are tested the same way, so each test is here once. Each part above points to its own.
Zener diode
Diode range for the forward check, part lifted, red probe on the anode. A bench supply for the Zener voltage.
Working, it reads
About 0.6 to 0.8 V forward and open in reverse on the diode range. Its Zener voltage shows only on a supply: feed it through a resistor that sets about 5 mA, cathode to positive, read quickly, and it should hold near its rated voltage.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- Open both ways, forward too: failed open.
- Holds well off its rated voltage on the supply test: drifted.
- A soft knee, or a voltage that creeps on the supply test: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A meter's diode range stops at about 2 to 3 V, so almost every Zener reads open in reverse on it, good or bad; a 3 V meter may just show a 2.4 or 2.7 V part. Above about 3 V the meter cannot tell a Zener from a plain diode.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Schottky diode
Diode range, part lifted or one leg off the pad. Red probe on the anode.
Working, it reads
About 0.15 to 0.45 V anode to cathode, roughly half a silicon diode, and open the other way.
Dead, it reads
- The same reading both ways round, near 0 V with a continuous beep or the same middling value: shorted.
- A reading the wrong way round as well: leaky.
- Open both ways: failed open.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A large Schottky can read about 0.1 V forward and beep like a short, and leaks a little the wrong way when good, more when warm. It is shorted only if it reads the same both ways. Measure it cold, beside an identical cold one.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Bipolar transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
From the base, one probe colour reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
TVS or ESD protection diode
Diode range, from the protected line to ground, part lifted if you can.
Working, it reads
A one-way part reads about 0.6 to 0.8 V forward and open in reverse. A two-way part reads open both ways. Arrays with several lines read as the datasheet's diagram draws them.
Dead, it reads
- From the line to ground, the same reading both ways, near 0 V with a continuous beep: shorted.
- A reading both ways on a one-way part: leaky.
- A one-way part open both ways: failed open.
- On the board
- , a line reading shorted to ground can be this part or anything else on that line. Lift it: if the short goes with it, it has failed.
- Compare:
- The same part on the next line or connector pin is the healthy reading to compare with.
- Watch for:
- A two-way part reads open both ways when it is good, exactly like one that has failed open. The meter cannot tell them apart; an identical part on the next line can.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Integrated circuit
Voltage with the board powered; ohms from each pin to ground with it off.
Working, it reads
Supply pin at its voltage and the output doing what the datasheet says. Readings between pins depend on the part.
Dead, it reads
- A pin near 0 Ω to ground or to the supply pin where an identical part does not read that: failed short.
- Supply present, output stuck: failed, or its load has.
- On the board:
- A pin shorted to ground on the board can be anything on that net. Lift the pin to be sure.
- Compare:
- The surest reference is the same IC on a working board, measured pin by pin.
- Watch for:
- Its protection diodes can read like junctions between pins, even like a transistor. That proves nothing either way.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
Voltage regulator
Voltage, board powered, black probe on ground. Then ohms with the power off.
Working, it reads
Input pin at the supply, output pin at its rated voltage, and the enable pin high if it has one.
Dead, it reads
- Output equal to the input: the pass element has shorted. Everything after it may have taken the full input.
- Input present, enable high, no output: failed open, or holding itself off into a shorted load. Power off and measure output to ground.
- Power off, input to output near 0 Ω: shorted.
- On the board:
- An output at 0 V is often a shorted load with the regulator in current limit. Lift the output pin: if the short stays on the board, the regulator may be fine.
- Compare:
- The same regulator on another rail or another board shows the right voltages and the right resistances.
- Watch for:
- Makers put input, output and ground on different pins in the same package, so take them from this part's datasheet. Diode or ohms readings between its pins say little; check it powered.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
PNP transistor
Diode range, part lifted or its base leg off the pad.
Working, it reads
Black probe on the base reads about 0.6 to 0.75 V to the emitter and to the collector, and open the other way round. Collector to emitter reads open both ways.
Dead, it reads
- Collector to emitter the same both ways, near 0 V with a continuous beep: shorted. The commonest failure.
- The base the same both ways to another pin, near 0 V or a middling value: a shorted junction.
- Only one junction reads, or none: a junction has failed open. It then looks like a diode.
- A reading the wrong way round, where it should be open: leaky.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
- Watch for:
- A pair of diodes with a common pin reads just like a transistor, and some transistors carry a built-in diode or resistor. The datasheet says which.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
This part
Diode range and ohms range, part lifted.
Working, it reads
Depends on what it is. The datasheet, or an identical part, says.
Dead, it reads
- Between two pins, the same reading both ways, near 0 V with a continuous beep: shorted.
- Open between every pair of pins: failed open, or a part that reads open when working.
- On the board
- this is a first look only: the meter reads every path between those pins, and a short can be a neighbour. Lift one leg before you condemn it.
- Compare:
- If an identical part sits elsewhere on the board, measure it the same way: that is what this one should read.
A dead part still carries its marking. A short or an open says it has failed, not that it is a different part.
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